Some more water has passed under the oul bridge. As I now do two jobs during the week, as well as helping to look after a Thoroughbred racehorse at weekends, modelling time has been severely cut down, but I haven't been totally idle.
Richard McLachlan of the IRRS has stumbled across some clearer motion drawings for the "S" - these are marked Dundalk drawing no.s 202N and 203N. He initially thought that they dated from the time when the "S" and "S2" were rebuilt in 1938, but the markings clearly show they were done at the end of 1925. With some of the known dimensions, I managed to reduce one down to 4mm scale, and the resultant copy is tiny but still just about legible!
The drawings also confirm that the distance between the frames is 4ft 8ins, so my original Maplin jig-spacer width of 16mm is almost there, though I am wondering if a few washers might help pad things out.
There are still a couple more drawings that I need - mostly of the cylinder block (103S and 105S), which is where things get interesting because the SSM kit smokebox frame partly extends downwards into the space where the piston valves of the inside cylinders should be!
I did manage to buy Martin Finney's inside motion kit for the LSWR T9, and was mighty pleased to find that the crossheads are almost exactly the right "+" cross-section for the "S", the matching slidebars and piston rod glands are adaptable, whilst the motion bracket looks like it could be split and widened to fit between the frames of the "S". I can use the cranks from the GW 1854/2721 inside motion kit as these are near-identical in shape to those on the "S".
This leaves the connecting rods themselves; it's 6ft 6ins (26mm in 4mm scale) between the centre of the "little end" and the centre of the "big end", so whether I adapt the rods from the GW or LSWR loco is not that important - the plain fact is that both types will need modifying!
At the moment the only scratchbuilt parts would appear to be the rockers and their brackets, as well as the back-end of the cylinder block.
A bit of work has been done on the cab - mainly the front overlay and the rear splasher tops:
It is important not to have any of it lopsided - all of the various holes and slots must line up with those on the inner cab structure, so it's out with the hairgrips again:
I found it was better to tack-solder the overlay in place before trying to form the splasher tops.